Giant pulsations belonging to the Pc5 frequency band were conceived by Rolf (1931). Such pulsations are influenced by magnetospheric processes produced by the solar wind. The purpose of this study is to investigate the Pc5 ULF waves and their relationship to solar parameters and geomagnetic indices, respectively, utilizing data from ground-based magnetometers and data provided by Operating Mission as Nodes on the Internet (OMNI). Magnetic observatories over Earth’s surface reported intense long-period ULF activity on 19 28 February 2014 and 22-23 June 2015. We discovered a highly significant correlation between global Pc5 ULF waves and other interplanetary parameters, as well as a clear peak-to-peak correspondence during storms. We performed continuous wavelet transform (CWT) on the Pc5 integrated power (Ipow) and discovered that the majority of the intense Pc5 spectra are localized within the 64-256 minute Fourier period band. Our results suggest that geomagnetic fluctuations observed at low latitudes do not originate locally but rather are a reflection of global geomagnetic field variations with primary sources in the magnetosphere and high latitude ionosphere, which is consistent with the study of Gupta (1976). We discovered only nominal effects of IMF Bz on Pc5 pulsations, despite its southern counterpart being widely believed to be the principal driver of geomagnetic storms. Additionally, we discovered a moderate effect of solar wind pressure on Pc5 pulsations. A cross-correlation study, on the other hand, indicated a strong and positive association between Pc5 pulsations and solar wind velocity without lag for both geomagnetic activities.

The plasma environment of Mars is highly influenced by crustal remnant magnetism in the planet. In this work, we do statistical analyses of MAVEN and MGS data to study whether the ionospheric plasma flow can move crustal magnetic field lines, by advection. Due to the day-tonight flow of the plasma, the magnetic field lines are expected to be dragged away in anti-solar direction, causing a shift between observed and modeled field. The results show that a small shift can be observed above weak anomalies on the Northern hemisphere, where the ionospheric plasma flow is less perturbed by strong magnetic fields. To investigate the relative forces between the moving plasma and the crustal field, we also calculated dynamic, magnetic and thermal pressures, since they are involved in the advection process. In general, the dynamic pressure is lower than the other two, but this does not mean advection cannot occur, because the process is not simply a pressure balance, but a diffusive process. The calculation shows that, if advection occurs on Mars, the speed at which the crustal field lines are displaced is much smaller than the speed of the ionospheric plasma flow.

Reanalyzing Cassini radio observations performed during Jupiter’s flyby of 2000-2001, we study the internal (rotational) versus external (solar wind) control of Jupiter’s radio emissions, from kilometer to decameter wavelengths, and the relations between the different auroral radio components. For that purpose, we build a database of the occurrence of Jovian auroral radio components bKOM, HOM and DAM observed by Cassini, and then frequency-longitude stacked plots of the polarized intensity of these radio components. Comparing the results obtained inbound and outbound, as a function of the Observer’s or Sun’s longitude, we find that HOM & DAM are dominantly rotation-modulated (i.e. emitted from searchlight-like sources fixed in Jovian longitude), whereas bKOM is modulated more strongly by the solar wind than by the rotation (i.e. emitted from sources more active within a given Local Time sector). We propose a simple analytical description of these internal and external modulations and evaluate its main parameters (the amplitude of each control) for HOM+DAM and bKOM. Comparing Cassini and Nançay Decameter Array data, we find that HOM is primarily connected to the decameter emissions originating from the dusk sector of the Jovian magnetosphere. HOM and DAM components form a complex but stable pattern in the frequency-longitude plane, that remains to be modelled. HOM also seems to be related to the so-called ‘lesser arcs’ identified by Voyager. bKOM consists of a main part above ∼40 kHz in antiphase with HOM occurrence, and detached patches below ∼80 kHz in phase with HOM occurrence.

The Time-of-Arrival (ToA) of coronal mass ejections (CME) at Earth is a key parameter due to the space weather phenomena associated with the CME arrival, such as intense geomagnetic storms. Several approaches to estimate the ToA based on kinematical parameters derived from single- and multi-viewpoint white-light coronagraph observations have been proposed and implemented, particularly in the last decade. Despite the incremental use of new instrumentation and the development of novel methodologies, ToA estimated errors remain above 10 hours on average. Here, we investigate the prediction of ToA of CMEs using observations solely from heliospheric imagers, i.e., from heliocentric distances higher than those covered by the existent coronagraphs. To that aim, we analyse 14 CMEs observed by the heliospheric imager HI-1 onboard the twin STEREO spacecraft to determine their front location and speed. Outside the field of view of the instruments, we assume that the dynamics of the CME evolution is controlled by the aerodynamic drag, a force that comes from the interaction with particles from the background solar wind. We found a CME ToA error mean value of 0.4+-7.3 hours ToA and a mean absolute error of 6.1+-3.6 hours in a set of 14 events. The results we found here illustrate that observations from HI-1 allow us to estimate the ToA with similar errors than observations from coronagraphs.